This paper investigates users' perceptions and experiences of an anonymous digital payment system (Bitcoin) and its influence on users in terms of usability and security in comparison to other non-anonymous payment systems such as credit/debit cards. This paper identifies users' perceptual differences in terms of usability and security. Two versions of user survey are used to collect data, which reveal significant differences in users' perceptions of credit/debit cards and Bitcoin. The usability attributes of both systems examined show that respondents perceive the usability of credit/debit cards to be higher than Bitcoin. This has a great negative influence on users' security perceptions of Bitcoin. We conclude that Bitcoin, as a crypto-currency, is still in its infancy and requires user education and a new way of thinking. The study recommends developing users' mental models to deepen developers' understanding of anonymous digital payment technology and improve user-centred design. We also make recommendations with respect to e-government services that may be developed relying on crypto-currencies.

Most governments implement the latest information communication technology (ICT) toimprove the online experience of their citizens and businesses. Governments put great effort into providing user-focused services that are usable, secure and accessible by portable and wireless devices (e.g. tablets, smart phones etc.). However, such devices bring with them specific problems of usability and security that affect how users interact with government digital services (GDS). This paper presents a systematic mapping study, investigating the existing problems of usability and security of GDS accessed through smart devices. It aims to uncover what evaluation methods have been used by researchers and investigate how the trade-off between usability and security is assessed in the context of GDS accessed through smart devices. The paper summarises the current knowledge available with regards to this trade-off over the last ten years. The results of the mapping study help identify several research gaps, leading to areas for new research in the domain of usability and security in the context of GDS.